The present invention relates to underwater distance measurement devices. More particularly, the present invention relates to portable, hand-held devices for measuring underwater distances such as surface to floor distances.
Boating, fishing, and diving enthusiasts often desire or require information regarding water depth and/or distances to submerged objects. Toward that end, various sonar measurement devices for mounting on boats have been proposed, including devices disclosed in U.S. Pat. Nos. 3,752,431 to McBride, 4,152,690 to Veatch, 4,282,590 to Wingate, and 4,285,485 to Burke. While the proposed devices are generally effective for obtaining desired measurements, they suffer from the requirement that they be permanently or semipermanently mounted on a boat at particular locations on the boat. The mounting location, however, may be inconvenient in many circumstances. Moreover, by requiring (semi-) permanent mounting, the devices are subject to theft, accidental damage (especially on small vessels), or at the very least, continued inconvenient mounting and dismounting procedures.
Portable, hand-held sonar-type depth determination apparatuses overcome many of the problems of the mounted devices of the art. Examples of such portable devices include U.S. Pat. Nos. 2,935,728 to Morgan, 3,123,798 to Holloway et al., and 4,281,404 to Morrow, Jr., et al. In particular, the Morrow, Jr. et al. patent discloses a hand-held, pistol shaped depth finding apparatus having a transducer, an electronics package with a liquid crystal display, and a electromechanical trigger. The water depth is found by immersing the barrel end of the pistol shaped device, pressing the trigger, and reading the depth on the LCD which is mounted where the hammer would be on a hand-held firearm.
While overcoming some of the problems of the art, the existing hand-held depth determination devices introduce additional problems. For example, in the Morrow, Jr. et al, device, the close proximity of the handle having the trigger to the transducer end of the barrel makes it highly possible, if not probable, that the handle will become wet and be difficult to hold, and that the user's hand and arm will have to be immersed in cold or foul water. Also, due to the length of the prior art device, and due to the fact that its LCD is mounted such that the user's eyes must be directly behind the device to read it, the user will have to hang over the side of all but the smallest vessel to use the device. Moreover, where the surface of the water is beyond arms length of the user, the hand-held device of Morrow, Jr. et al. will not be usable. Even where the water surface is close, accurate readings may not be obtained, as it has been found by the applicant hereof, that except in the calmest of seas, the transducer should be immersed to a depth of at least six inches below the surface of the water to avoid the rising of the transducer out of the water as the vessel rolls. Furthermore, in the Morrow, Jr. et al. device, the compartment containing the electronics package is directly connected with the compartment containing the batteries. While the entry to the battery compartment has a waterproof closure system, both water and water vapor can enter the battery compartment whenever the battery compartment is open to change batteries, or whenever the closure system fails. As a result, water and water vapor can enter the electronics package and cause the entire unit to fail permanently.